Described below are bi- or polynuclear metal complexes as p-dopants for organic electronic matrix materials.
Within organic electronics, it is possible to identify two important commercial fields of technology. The first field of technology is concerned with uses of organic matrix materials for conversion of light to electrical current and vice versa, and the other field is focused on the construction of electrical components by organic semiconductor material. Examples of the former category are, for example, photodetectors and organic solar cells, shown in schematic form in FIG. 1, which convert light to an electrical signal or to electrical current, and organic light-emitting diodes (OLEDs), which can generate light by organic electronic materials (see FIG. 2). In the second field of technology are, for example, organic field-effect transistors, shown in schematic form in FIG. 3, in which doping reduces the contact resistance between electrode and semiconductor material, or bipolar transistors.
A common factor to all the applications is that they include, as important functional component, electrical transport layers which have different conduction mechanisms depending on their composition. In general, a distinction is made between intrinsic p-conductivity (hole conductivity) and n-conductivity (electron conductivity) of the organic materials. Since the electrical properties of these organic substance classes are generally insufficient for high-efficiency utilization of the components, they are admixed with additional compounds which are intended to improve the electrical properties of the layers. This is typically done by doping with metallic or further organic compounds. One approach to achieving significant improvements in conductivities is the addition of metal complexes and especially the addition of transition metal complexes.
For example, WO 2005 086251 describes dopants for production of n-conductive layers which may have structures including the following:

The structure of this compound class is also referred to in the literature as “paddle wheel complex”. More particularly, the publication describes the use of a metal complex as n-dopant for doping an organic semiconductive matrix material to alter the electrical properties thereof. The compounds presented are said, with respect to the matrix material, to be usable as n-dopants.
Another way of using Lewis-acidic metal complexes to dope p-conductive transport layers is given by Endo et al. (Jpn. J. Appl. Phys. vol. 41 (2002) L358-L360). This reference describes organic electroluminescent devices having a p-conductive layer which are prepared by co-doping from FeCl3 and arylamine derivatives, for example N,N′-dinaphthyl-N,N-diphenylbenzidine (α-NPD). However, significant disadvantages for the component are also described therein, such as extinguishment of the luminescence and an increase in intrinsic absorption.
A further way of configuring organic semiconductors for bipolar field-effect transistors by doping is additionally disclosed in DE 102010041331.